Welding systems used in industrial welding cells typically include a variety of specialized pieces of equipment that are interconnected to perform a weld. The equipment can include, for example, a welding power source, a wire feeder, and automation equipment, such as an automation controller, robot, or fixed automation components. Weld cables carry power and wire to a workpiece to be welded, and are a necessary component of the system. Communications between the components and other devices are typically also carried by wires or cables. A typical system is shown, for example, in FIG. 1. Here, a welding power source 108 is shown connected to a robot controller 105, robot 101, wire feed motor 102, and a gas valve 103 through a series of cables 104, 106, and 107. Weld cables 109 and 112 provide power to the workpiece 110 and corresponding wire electrode. A voltage feedback cable 109 provides feedback signals to the power source 108. The remaining cables generally carry communications, including command signals and feedback signals, between the components of the welding cell.
There are advantages to carrying communication signals by wire, as shown here. Wired communications are typically more immune to noise from electromagnetic fields associated with welds, and disturbances caused by associated equipment, like high frequency starters. Because welding equipment is used in an industrial environment, however, cabling causes a number of problems. For example, it is often important to minimize the overall size or footprint of a welding cell. Cables are problematic, however, because when routed between the various pieces of equipment, the cables can reduce the area available for a weld operator to move within the cell. Additionally, when improperly positioned, wires and cables can be damaged by forklifts and other equipment used in the industrial environment.
It is, therefore, desirable to interconnect the welding equipment in a welding cell or other installation using wireless communications. The electrical and electronic circuits used in welding equipment, however, are generally encased in steel housings or cabinets. Typical wireless communications modules or systems use on-board chips or printed antennas that are formed on a printed circuit board, which are not effective in a steel housing, and therefore need to be mounted externally. Industrial equipment is often subject to environmental damage, when operators, for example, use the equipment to store tools, as a platform for welding, or for other unplanned uses. External antennas, therefore, can be easily damaged.
Furthermore, because the equipment is used in confined, typically indoor locations, and closely spaced to other welding cells and equipment, there is often no clear line of sight between a transmitter and a receiver in the welding system. Instead communication signals are reflected or “bounced” along multiple paths before finally being received. Each of these bounces can introduce phase shifts, time delays, attenuations, and distortions that can destructively interfere with one another at the aperture of a receiving antenna. As described above, moreover, the welding environment is particularly prone to noise problems. This issue is exacerbated in many countries where the power level of wireless transmissions is limited by law. Additionally, the close proximity of adjacent cells can lead to interference and confusion about the appropriate wireless network to be used.
The disclosed system addresses these and other issues.